Integration tests — adaptive+hybrid on constrained resources #47
Description
No integration tests exercise adaptive+hybrid (Auto protocol) with real sub-engines.
Tests added:
- TestAdaptiveAutoProtocol: H1 + H2C + mixed parallel
- TestAdaptiveAutoSingleWorker: single worker + small ring (arm64 crash scenario)
- TestAdaptiveSwitchUnderLoad: ForceSwitch + verify new engine serves
- TestAdaptiveResourceCleanup: shutdown with no double-decrement
- TestAdaptiveConstrainedRing: minimal SQERingSize (1024)
- TestEpollPauseResume: epoll pause/resume in isolation
- TestSwitchDuringHighCPU: synthetic CPU at 0.87, verify no false freeze